Alarm raised as mystery pest destroys Mississippi Delta marsh

Updated on Apr 11, 2017 at 11:36 AM CDT

Eric Newman, a Venice fishing guide, holds a dead stalk of roseau cane on Friday, April 7, 2017, near what was a large stand of the wetland grass but is now open water. Critical wildlife habitat and a bulwark against erosion, the cane has been hard-hit by an invasive pest in recent months. (Photo by Tristan Baurick, NOLA.com | The Times-Picayune)

Dead stalks are all that remain of a large stand of roseau cane near Venice in Plaquemines Parish on Friday, April 7, 2017. (Photo by Tristan Baurick, NOLA.com | Times-Picayune)

Healthy roseau cane stands in Baptiste Collette Bayou on the Mississippi River Delta, photographed Friday, April 7, 2017, have turned to open water in a matter of months. (Photo by Tristan Baurick, NOLA.com | The Times-Picayune)

An invasive insect, thought to be a type of scale, has killed thousands of acres of roseau cane in the Mississippi River Delta. Scientists aren't sure how to stop its spread. (Photo by Tristan Baurick, NOLA.com | Times-Picayune)

Near Venice, Rancher Earl Armstrong inspects a stand of roseau cane hit hard by an invasive pest on Friday, April 7, 2017. (Photo by Tristan Baurick, NOLA.com | The Times-Picayune)

Fishing guide Eric Newman passes dying stalks of roseau cane in the Misssissippi River Delta on Friday, April 7, 2017. Critical wildlife habitat and a bulwark against erosion, the cane has been hard-hit by an invasive pest in recent months. (Photo by Tristan Baurick, NOLA.com | Times-Picayune)

Eric Newman speeds through the maze of bayous at the
Mississippi River
's mouth with the confidence of someone who's done this for decades. He points to prime spots to catch redfish, where crabbers go for blues and the grassy channel where his grandfather had a fishing camp.

Suddenly, he slows his boat. The intimately familiar has just become alarmingly unfamiliar. "Two months ago, this was beautiful," he said, easing past mud flats that had been lush with eight-foot-tall marsh grass. Clumps of blackened roots are all that's left. "Looking at it now, it just blows me away. I don't even know how to navigate it."

The likely cause: a foreign bug that's sucking the life-giving juices out of the cane. State and university scientists have been trying for weeks to identify the species, thought to be a type of scale or mealybug. As yet there is no plan to eradicate it.

The roseau cane plague is only the latest in the long line of threats to Louisiana's crumbling coast. Storm surge,
rising seas
and wetlands canals dug by
oil and gas explorers
are considered the main culprits, so the state is pushing a $50 billion, 50-year
master plan
to mitigate further losses.

At the
Pass a Loutre Wildlife Management Area
on the far south end of the delta, the cane die-off is especially bad. "Of the the 110,000 acres we have there, [the insect] has affected easily 80 percent," said Vaughan McDonald, a coastal biologist with the state Department of Wildlife and Fisheries.

State officials have kept relatively quiet about the pest invasion as they try to come up with solutions. But the damage - and the wider implications - are becoming hard to ignore. The delta has one of the world's largest stands of roseau cane. The cane is, quite literally, what holds the delta together. Its disappearance could hasten the erosion that's fast turning land into water.

"Where this is happening, in the delta of the Mississippi, is one of the largest continuous stands of [roseau cane] in the United States," said Irving Mendelssohn, professor emeritus of Louisiana State University's College of the Coast and Environment. "You'd have to go to central Europe and the Danube River to see such an extensive stand."

Known for its soil-building prowess, the cane serves as a living, growing bulwark against land loss. That's of vital importance to
Plaquemines
, which has lost about 250 square miles over the past 60 years to
coastal erosion
and land subsidence.

The cane resists floods and spreads easily. Its extensive root system acts to both "lift" and hold soil in place, and its dense concentration of stalks catch and hold passing river sediment. "More than any other marsh species, [roseau cane] has the potential to withstand sea level rise," Mendelssohn said.

LSU entomologist Rodrigo Diaz is leading the effort to identify the insect. He's hesitant to discuss the issue in detail "because there are so many unknowns."

It's clear the aphid-like bug is not native to North America. It might have hitched a ride aboard a ship or blown in on storm debris. Scientists are looking into how environmental factors, including
climate change
, weather patterns and water chemistry, might have weakened the cane or strengthened the insect. Oil and other forms of pollution have not been ruled out. No one is sure how to halt the incursion.

About the size of a flea, the insect is white or translucent. It is often found under cane leaves or tucked into stalk crevices. "They look like dust particles, but they're moving," Pass a Loutre manager Trevor Victoriano said.

High concentrations of the insect were first noticed during the fall in Pass a Loutre. Cane died in the management area, but new growth quickly appeared, giving hope that the problem was temporary.

"But then even the healthier cane had crawlers on them," Victoriano said. "Now its hard to find a spot with no sign of the parasite."

Joey Breaux, an environmental specialist with the state Department of Agriculture and Forestry, said roseau cane dies back naturally in winter, but the plant should have reached full or near-full regrowth by now. In many parts of south Plaquemines, the plant has reached just 5 percent or 15 percent regrowth. His department has documented cane die-off as far north as the Bohemia Spillway.

"It's everywhere," said Earl Armstrong, a lifelong resident of the delta. To prove the point, he grabbed a stalk of cane from a yard north of Venice. Cracking open a dry stalk, he pointed to the telltale signs of the bug: tiny black stains and the dry shells of dead bugs.

Armstrong, a cattle rancher and former commissioner of the Plaquemines Soil and Water Conservation District, said his family has, for four generations, survived floods and devastating hurricanes. "But this cane problem is the worst we've ever had," he said. "We're going to lose land twice as fast."

Cane die-off will make the area less resistant to storms and could reshape the delta's geography, making ship navigation difficult in one of the most heavily trafficked areas of the United States. Communities such as Venice, and nearby pipelines and other infrastructure of the oil and gas industry, could be in danger.

Newman, a charter fishing boat captain, worries about his livelihood. The delta is a top destination for recreational fishing, an industry that generates $1.8 billion in Louisiana each year.

"If there's no cane, there's no fish," said Newman, whose most popular catch, redfish, use cane to ambush their prey. "This makes me nervous for my business and all of my friends' businesses."

Harm to the fishing industry has broad implications in south Louisiana, from gasoline stations and restaurants to marinas and bait shops. "People come from all over the world to hunt and fish down in Venice," said Anthony Puglia of Puglia's Sporting Goods in
Metairie
. "It's really the main location. If there's no roseaus, that will definitely affect everything."

Land loss in Pass a Loutre would lengthen an already arduous journey for millions of birds traversing the
Gulf of Mexico
. "We're the end of the road for a lot of migratory ducks and other birds," said McDonald, the Wildlife and Fisheries biologist. "Without roseau cane, it would be a different place - possibly just a boundary line on a map."

Until scientists know more about the pest, solutions are hard to come by. "It's frustrating because we want management options before more damage occurs," said Breaux of the Agriculture Department.

His best idea: controlled marsh fires. The insect would die and the cane would likely quickly recover. But oil and gas pipelines across the delta, including Pass a Loutre, make the option risky. "We'd have to be on top of our game with all the oil infrastructure there," he said.

Other ideas include spraying insecticide or introducing a predator in the same way ladybugs are deployed to counter aphid outbreaks.

Armstrong is impatient. He wants action. "Cane is the backbone of the lower delta," he said. "If we lose our cane, we're out in the open."